Blood flow through the circulatory system can be restricted when a thrombus (blood clot) develops inside a blood vessel or when an occlusive thromboembolism occurs. A thrombus is generally formed from platelets and fibrin to prevent loss of blood due to an injury to the blood vessel or bodily tissue. A thrombus may also form directly on an atherosclerotic lesion within a blood vessel and lead to thrombotic occlusion in situ. Serious complications can occur if a thrombus grows too large and obstructs too much of the blood vessel. The thrombus may also break loose, forming an embolus that can lodge in another part of the body or distal vasculature, obstructing blood flow and potentially causing irreversible harm to organs or death.
Ischemia is a reduction in blood flow to an organ or tissue, causing damage due to a lack of sufficient oxygen or fuel being delivered to the cells. One type of stroke (an ischemic stroke) occurs when a cerebral vessel is obstructed (such as by a thrombus or an embolus), reducing blood flow to a specific region of the brain. A blockage of this type can quickly lead to irreversible damage to brain tissue and death. It can be seen, therefore, that there is a great need for effective treatment options to dissolve or otherwise remove/reduce blood clots to increase the blood flow to organs such as the brain and to resolve any thrombus which occurs in situ or breaks loose to cause an embolism.
Thrombolysis and fibrinolysis (the break-up or dissolution of a blood clot) generally involves the use of thrombolytic and fibrinolytic drugs. The drugs activate an enzyme which breaks down the protein holding the clot together, making the clot soluble and less durable. The treated clot is then broken up and removed from the blood vessel either mechanically or through natural physiologic processes. These medications can be delivered with intravenous and intra-arterial injections.
Data has been emerging regarding the use of exogenous application of different forms of energy to assist in thrombolysis. One such application energy is the combined dissolving of thrombus in brain ischemia using transcranial ultrasound and systemic tissue plasminogen activator (CLOTBUST trial; J Neuroimaging: 14 (2): 108-112). Such a treatment involves the external application of diagnostic ultrasound along with the use of a tissue plasminogen activator (tPA) protein to accelerate flow improvement and achieve faster and more complete resolution of the thrombus. Other treatments include the use of lasers or ultrasound (US) catheters positioned endovascularly adjacent to the affected area to accelerate the dissolution of the thrombus. Endovascular devices have also been used adjunctively with chemical thrombolysis and fibrinolysis or primarily to treat a thrombus; however, distal access to a thrombus is limited due to the large size of available devices relative to small distal vessel diameters and due to the difficulty of maintaining proximal support of the access system that allows entry into the distal tortuous anatomy.
It would be desirable to provide an apparatus for and method of allowing an energy such as electromagnetic energy to be applied in close proximity to a distal thrombus to aid in the dissolution of the thrombus or aid in the localization of thrombolytic and fibrinolytic drugs to the thrombus.
The distal aspect of endovascular guide wires are frequently shaped by the user to achieve better navigability into the distal vascular anatomy, but conventional methods of shaping (e.g., rigid shaping mandrels) would impart trauma to elements that could be coupled to the guide wire, thereby causing device failure.
It would be desirable to provide a device for shaping the guide wire without imparting trauma to the guide wire that may cause device failure.